Experimental Studies of Scale Model Drag Embedment Anchors (DEAs) Subjected to Impulse Forces

Date of Award


Degree Type


Degree Name

Master of Science (MS)


Civil and Environmental Engineering


Samuel P. Clemence


Anchors, Drag, Dynamic, Impulse, Scale, Tests

Subject Categories

Civil and Environmental Engineering


The goal of this research is to increase the understanding of the performance of drag embedment anchors (DEAs) under a dynamic impulse force to inform the design of mooring systems subject to impulses. The research methodology included scale-model testing, data analysis, and comparison with other performance predicting methods. The investigation was conducted on a 1/6th scale model Danforth-style drag embedment anchor in cohesionless soil subjected to an in-plane impulse force. For all impulse forces less than 0.8 seconds, the DEA consistently held up to 200% of the maximum quasi-static holding capacity. For very short impulses, less than 0.3 seconds, the DEA held up to 600% of the maximum static holding capacity. The DEA did not continue to penetrate along a predicted anchor trajectory when subjected to impulse forces. Instead, it exhibited a rotational motion. Based on the results of this investigation, it is believed that the inertial forces of the soil and anchor, which oppose the acceleration of the impulse, develop a moment. This causes the anchor to rotate. The resulting change in anchor orientation alters the balance of forces restraining the anchor and, under certain conditions, the anchor may become unstable and fail under the impulse force. Further field testing and computer modeling of the proposed inertial force method of dynamic equilibrium is recommended to predict its reliability under expected impulse loading.

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